Page 1 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Follow-up Efforts on SEC-00192, Rocky 

Flats Plant Tritium Issues

White Paper

Rev. 3 

National Institute for Occupational Safety and Health 

December 28, 2015

J. S. Bogard, E. M. Brackett, Mutty Sharfi, Tom LaBone, Nancy Chalmers and Dan Stempfley 

Oak Ridge Associated Universities Team

Reviewed by James W. Neton Ph.D., CHP and LaVon B. Rutherford, CHP 

Division of Compensation Analysis and Support 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 2 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Introduction

This is a summary of the initial and secondary tritium follow-up efforts performed by the 

National Institute for Occupational Safety and Health (NIOSH) Division of Compensation 

Analysis and Support (DCAS) and Oak Ridge Associated Universities Team (ORAUT) in 

support of the SEC-00192 Rocky Flats Plant (RFP) Special Exposure Cohort (SEC) Evaluation 

Report (ER) presented to the Advisory Board on Radiation and Worker Health (Advisory Board) 

in September 2012. 

As part of the initial follow-up, additional document data captures and personnel interviews were 

performed (classified and unclassified) to: (1) clarify the existence of tritium on site and 

associated personnel exposures; (2) expand the investigation on tritium bubbler sampling; (3) 

confirm the existence of shipping container tritium surveys; and (4) confirm the type and amount 

of sampling analysis performed in Building 123. These initial follow-up efforts were performed 

to validate the tritium bounding method for the SEC-00192 RFP ER (which uses information 

from the 1973 tritium incident as the maximum exposure scenario), and to provide more precise 

estimates of doses due to tritium.

NIOSH requested that ORAUT conduct a secondary follow-up effort and evaluate all available 

documentation/data in light of the additional information captured during the initial effort (this 

additional information was included in Rev. 1 to the initial tritium follow-up paper). NIOSH 

requested that ORAUT:

• analyze RFP occupational tritium exposures prior to 1973 (see Appendix 1). 

• determine the best approach for tritium dose assignments for 1973 and later (see Appendix 

1).

• provide an example tritium dose reconstruction using this approach (see Appendix 1). 

• prepare responses to comments from the Advisory Board Work Group and Sanford Cohen & 

Associates (SC&A) on the RFP Tritium White Paper (see Appendix 2). 

In Rev. 2 of the initial tritium follow-up paper, ORAUT was also asked to: 

• revise the best approach for tritium dose assignments for 1973 and provide additional 

explanation on the reconstruction of organically-bound tritium (OBT) using urine bioassay in 

IMBA (see Appendix 1). 

• comprehensively close out the issue of RFP tritium exposure after 1973 by evaluating the 

evidence of a robust workplace-monitoring program (see Appendix 3). 

In this most recent revision (additional information included in this Rev. 3 to the initial tritium 

follow-up paper), ORAUT was also asked to: 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 3 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

• address the Board Working Group review comments and revise the approach for tritium dose 

assignments for 1973 and later (revision impacts Appendix 1, Part II and III). 

Initial Follow-up

Introduction

A review of all RFP-related Site Research Database (SRDB) documents was performed to 

determine if any documents existed in that dataset that could expand on any of the issues raised 

regarding tritium. The documents relating to tritium monitoring at RFP were identified, 

including some tritium bubbler results, and some indication of tritium contamination surveys. 

There are multiple documents regarding four significant incident-related tritium releases that 

occurred in 1968, 1973, 1974, and 1977 (SRDB Ref ID: 8265, 8790, 24164, 24165, 24167, 

110900, 110901, and 110903). There are also post-1977 documents that confirm continued 

monitoring of tritium releases and residual tritium as a result of these four earlier releases.

There is also an SRDB document that provides information on post-1977 stack releases 

occurring in 1981 and 1986; both releases were considered small with no impact to site 

personnel or the immediate surrounding area (SRDB Ref ID: 110900). While some of the 

documents corroborated the classified interview issues addressed in the following sections of this 

white paper (i.e., bubblers and tritium contamination surveys), it does not appear that any of the 

new information supports the notion that there were any tritium levels that exceeded the 1973 

incident. Therefore, ORAUT finds no evidence disputing the use of the 1973 incident data as the 

bounding estimate for tritium at RFP, as presented in the SEC-00192 RFP ER. 

As stated in the SEC-00192 ER, RFP operations that were related to, or had potential exposure 

impacts associated with tritium included neutron generator operations (i.e., the use of tritiated 

targets), and returned pit operations. Subsequent post-ER classified interviews identified 

shipping container handling as a potential exposure source. 

The following was learned:

• The follow-up effort corroborated in at least one interview (SRDB 122907) and in two 

documents (SRDB 118369; 117274) the point made in the SEC-00192 ER that the 

stainless steel reservoir operation was a construction operation before the introduction of 

tritium, which occurred at other sites. RFP was responsible for constructing the 

reservoirs and shipping them to other locations where they were filled/used. 

• The follow-up effort corroborated that the neutron generator tritium target sources did not 

represent a source larger than the one represented in the 1973 tritium incident. 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 4 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

• The tritium-contaminated pits and shipping containers are considered directly related 

because the shipping container tritium was a result of tritium from the pits loaded in the 

containers. Because of potential classification issues, the assessment of this issue will be 

addressed later in this document under the more general term shipping containers rather 

than the term pits.

• A follow-up effort was directed to determine if there are any other scenarios with the 

potential to exceed the SEC-00192 RFP ER bounding approach. These scenarios are 

being assessed as part of the pre-1973 tritium shipping container exposure evaluation 

(discussed later).

The indications found in the available documentation and provided by the majority of 

interviewees, was that RFP did not work with tritium as a normal or usual process, and therefore, 

did not expect it on site. The RFP radiological program did very little monitoring for tritium 

prior to the 1973 incident because they felt they had limited tritium exposure potential. Changes 

to the program related to tritium monitoring were implemented as a result of the 1973 incident. 

It has been corroborated that tritium bubbler monitoring did exist on site as part of the usual RFP 

air-monitoring program before and after the 1973 tritium incident (SRDB 122907); however, the 

current information does not indicate how long before the 1973 incident bubblers existed on site. 

The available bubbler monitoring data are being evaluated for applicability in dose 

reconstructions. 

As indicated in the SEC-00192 ER, the site implemented a routine tritium bioassay program after 

the 1973 tritium incident, but discontinued the routine program in 1975 due to lack of positive 

bioassay results. The program was subsequently implemented on an as-needed or as-identified 

basis. This situation was corroborated in at least one personnel interview performed during this 

follow-up effort (SRDB 122907). 

Initial Follow-up: Tritium Bubblers

Significant information on the bubbler monitors was discovered during the additional follow up 

data capture efforts. There is some documentation in the SRDB that discusses the use of tritium 

bubblers. Based on the available data, including the most recent information (schematics and 

pictures of the tritium air sampling and monitoring equipment and processes [SRDB 122779 

through 122791]), there was a program that included the use of tritium bubblers to monitor 

enclosed and exhaust systems for tritium (SRDB 122466). As previously discussed, the exact 

start date for the use of bubblers has not been confirmed, but they did exist on site before the 

1973 incident (SRDB 122907). Most individuals interviewed were not well-informed on bubbler 

use or operation. 

The SRDB contains some tritium bubbler results (SRDB 111095; 122712) as well as detailed 

schematics and pictures of the units (SRDB Ref ID’s: 122691; 122692; 122693; 122787; 

122788; 122789; 122790). Based on these results, information discovered during the follow-up 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 5 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

research, and the interviews there is nothing to support the occurrence of a release event more 

significant than the 1973 incident. 

Table 1 below presents a summary of the Rocky Flats tritium bubbler information contained in 

the SRDB.

Table 1: Rocky Flats Tritium Bubbler Information in the SRDB

Category Type SRDB 

Ref ID Year File Description Comments

Tritium Monitoring 

Results, Procedures, 

and Occurrences

17824 1990-1991 Occurrence 

reports

Contains two occurrence reports involving 

inoperable bubblers, and one report of a 

Triton tritium air monitor that was shut off. 

None of the occurrences involved tritium 

releases.

Tritium Monitoring 

Results, Procedures, 

and Occurrences

24164 1976-1983 Tritium 

inventories 

and effluents

Contains an evaluation of tritium-release 

potential from a proposed neutron crate 

counter (1983); elevated tritium effluents 

from Bldg. 776/777 (January 1981); 

estimated inventory of tritium as surface 

contamination in glove boxes, ducts, and 

exhaust plenums in Bldg. 776/777 (1980); 

evaluation of ethylene glycol in place of 

water in tritium bubblers (1978); special 

study of tritium in ambient air (1976); a 

report, “Estimates of Maximum Tritium 

Releases to the Atmosphere from Operations 

at the Rocky Flats Plant” (1976); and a Call 

Report indicating that 0.058 μCi of tritium 

would probably be vented to the atmosphere 

for an experiment on May 20, 1974.

Tritium Monitoring 

Results, Procedures, 

and Occurrences

24307 1986 Procedure for 

effluent and 

room air 

tritium 

sampling

Operating procedure
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 6 of 45

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Category Type SRDB 

Ref ID Year File Description Comments

Tritium Monitoring 

Results, Procedures, 

and Occurrences

111095 1977-1981 Tritium 

bubbler 

sampling 

results

Log of analytical results for bubblers in 

operating areas, including room air and near 

downdraft tables. Most results are <100 

pCi/m3, but results exceed 1,000 pCi/m3 on 

several occasions in Bldg. 559 - Rm 102, and 

in Bldg. 881- Rm 283. The highest result 

appears to be 89,230 pCi/m3 in Bldg. 771 for 

the period May 11-18, 1978 (PDF pp. 92, 

93), although the measurement appears to be 

associated with a filter plenum or filter unit 

and not workplace air. NOTE: The bubbler 

location associated with the elevated result of 

May 11-18, 1978 was entered in the sample 

analysis log as “771 Fu 2”. Two incident 

reports found in the SRDB refer to the FU2B 

filter plenum or filter unit in Building 771 

(SRDB 17817, PDF pp. 285-287, 344-347; 

SRDB 17819, PDF pp. 363-365).

Tritium Monitoring 

Results, Procedures, 

and Occurrences

122466 2013 Documented 

interview with 

[Name 

redacted]

Includes a discussion of the different 

laboratories at Rocky Flats for analyzing 

tritium and other radionuclides in samples.

Tritium Monitoring 

Results, Procedures, 

and Occurrences

122712 1998 Lab report -

tritium 

activity in 

bubblers

Detailed analytical report from Thermo 

NUtech, including sample activity, counting 

uncertainty, detection limit, and total 

propagated uncertainty.

Tritium Monitoring 

Results, Procedures, 

and Occurrences

122907;

24167

2013 Documented 

interview with 

[Name 

redacted]; 

1973 incident 

report

Includes a discussion of the tritiated targets 

for laser fusion experiments and 

corroboration that bubblers were in use at 

several Rocky Flats locations prior to the 

1973 tritium-release incident.

Tritium Sampler 

Photos and Design 

Documents

122691 1973 Photos –

tritium 

operations at 

Dow

Relevance of photos to tritium monitoring or 

tritium operations is not apparent, except for 

one photo of a Triton tritium monitor.

Tritium Sampler 

Photos and Design 

Documents

122692 1977 Photos -

tritium 

monitoring

Good photos of sampling fixture for sealed 

cans and drums, Triton Model 955B tritium 

monitor, and bubblers mounted outside a 

glove box for sampling glove box air.

Tritium Sampler 

Photos and Design 

Documents

122693 1983 Photos –

tritium air 

sampling 

station

Labeled tritium-sampling assembly showing

building number, air flow rates, and water 

volume.
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 7 of 45

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Category Type SRDB 

Ref ID Year File Description Comments

Tritium Sampler 

Photos and Design 

Documents

122779 1974 Drawing 1 of 

8 - Tritium 

and iodine 

sampler 

assembly

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122780 1974 Drawing 2 of 

8 - Tritium 

and iodine 

sampler 

assembly

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122781 1974 Drawing -

Environmental 

tritium and 

radioiodine 

sampler 

details

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122782 1974 Drawing -

Environmental 

tritium and 

radioiodine 

sampler 

wiring 

diagram

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122783 1974 Drawing -

Environmental 

tritium and 

radioiodine 

sampler 

mounting 

detail

Engineering drawing

Tritium Sampler

Photos and Design 

Documents

122784 1974 Drawing -

Environmental 

tritium and 

radioiodine 

sampler onsite 

electrical 

hookup

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122785 1974 Drawing -

Environmental 

tritium and 

radioiodine 

sampler 

offsite 

electrical 

hookup

Engineering drawing
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 8 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Category Type SRDB 

Ref ID Year File Description Comments

Tritium Sampler 

Photos and Design 

Documents

122786 1974 Drawing -

Environmental 

tritium and 

radioiodine 

sampler onsite 

and offsite 

electrical 

hookup

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122787 1978 Drawing –

Tritium 

detector 

assembly

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122788 1978 Drawing –

Tritium 

detector 

details (1)

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122789 1978 Drawing –

Tritium 

detector 

details (2)

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122790 1978 Drawing –

Tritium 

detector 

details (3)

Engineering drawing

Tritium Sampler 

Photos and Design 

Documents

122791 1978 Drawing -

Tritium 

detector flow 

diagram

Engineering drawing

Initial Follow-up: Shipping Container Tritium Surveys

As part of the follow-up, additional research was performed regarding the issue of tritium 

contamination in shipping containers. This issue arose from one of the classified interviews 

(SRDB 122516). Tritium contamination in shipping containers was corroborated in an SRDB 

document (SRDB 111301); however, no actual contamination surveys have been found. The 

follow-up survey requirements and processes were corroborated in a follow-up interview in 

which the interviewee discussed implementing the shipping container tritium survey program in 

response to the 1973 incident (SRDB 122907). During that interview, the interviewee said that 

no tritium contamination was ever found. Other classified interviewees indicated that they had 

heard about shipping-container contamination, but they had no direct experience of it. A worstcase situation analysis of potential shipping-container contamination levels has been performed 

for comparison with the SEC-00192 ER bounding analysis in order to validate the ER’s 

bounding exposure scenario and to provide a more precise estimate for tritium dose prior to 

1973. This analysis is provided in Appendix 1. 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 9 of 45

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Initial Follow-up: Sample Analysis In Building 123

Analytical capability existed in both the production areas and in Building 123 (SRDB 122625), 

which housed the laboratories supporting worker health and safety (Industrial Hygiene and 

Health Physics) as well as the environmental programs (SRDB 122627). Samples collected in 

the production areas may have been analyzed either in the production laboratories or in Building 

123, depending on the anticipated level of analytes and the potential for contamination with 

plutonium or uranium, for which strong contamination-control practices were in place. Tritium 

samples from stack exhausts, which were filtered several times before sampling and release to 

the environment, were typically analyzed in Building 123. Samples collected in the work areas 

were analyzed in a production area laboratory to eliminate the possibility of introducing 

plutonium contamination into the Building 123 lab (SRDB 122627). Samples with a high 

likelihood of elevated tritium content might have also been analyzed in a production lab to 

prevent tritium contamination in the low-level Building 123 laboratories (SRDB 122624). 

Some effort was made prior to 1973 to use commercially-available tritium monitoring equipment 

(e.g., the vibrating reed spectrometer and tritium sniffers) (SRDB 110885; 122623; 122670; 

122671) or to develop an in-house capability (through development of specialized ion chambers 

or tritium concentration techniques, such as silica gel traps [SRDB 24648; 24680]). Liquid 

scintillation counting was reportedly used for quantitative analysis of a variety of radioactive 

materials in the production areas; it quickly became the technique of choice for tritium sample 

analysis after the 1973 environmental tritium release. Tritium sniffers continued to be used to 

indicate elevated tritium in the workplace, but they did not provide quantitative data of record. 

No results for tritium samples analyzed in the production areas have been captured, and only 

limited data are available from the Building 123 laboratories. ORAUT’s understanding of the 

criteria for determining where tritium samples were analyzed comes solely from interviews with 

former Rocky Flats Plant employees.

Initial Follow-up: Conclusion

The additional documents and interviews obtained during the post-ER follow-up efforts provide 

additional evidence of the potential for tritium exposures. However, the information also 

supports the case that estimates of potential tritium exposure that could have occurred prior to 

1973 are bounded by the exposure estimate for the 1973 event, and that more precise estimates 

are feasible.

Table 2 below lists the follow-up actions performed in support of SEC-00192. 

Table 3 further below lists the follow-up interviews performed in support of SEC-00192. 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 10 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Secondary Follow-up: Appendices 1, 2, and 3

In light of the additional information and data gathered during the follow-up effort and the Board 

Working Group reviews, NIOSH requested that ORAUT evaluate the available documentation 

and data to: (1) analyze RFP tritium exposures for 1959 1973; (2) determine the best approach 

for dose assignment for 1973 and later; and then (3) produce an example tritium dose 

reconstruction employing the best approach determined in the analysis. The results of this 

assessment are provided in Appendix 1. 

NIOSH also asked ORAUT to prepare responses to comments from the Board Working Group 

and SC&A on the RFP Tritium White Paper. These responses are provided in Appendix 2. 

NIOSH further asked ORAUT to comprehensively close out the issue of RFP tritium exposure 

after 1973 by evaluating the evidence of a robust workplace monitoring program. Such a 

program would support using the co-worker model discussed in Appendix 1, Part II. The 

evaluation of evidence for a workplace-monitoring program is provided in Appendix 3. 

Table 2: Initial and Secondary Follow-up Actions Performed in Support of SEC-00192

Category Type Date Activity or Paper Title Location

Initial Follow-up 

Actions

10/03/2012 Secure Discussions NIOSH (Cincinnati, OH)

Initial Follow-up 

Actions

10/28/2012 Data Capture LANL (Los Alamos, NM)

Initial Follow-up 

Actions

11/06/2012 

through 

11/07/2012

Eleven secure interviews with former 

RFP employees (see Table 3)

DOE-EMCBC (Denver, CO)

Initial Follow-up 

Actions

01/15/2013 

through 

01/31/2013

Eight follow-up telephone interviews 

with former RFP employees (see Table 

3)

Employee homes via telephone

Initial Follow-up 

Actions

02/03/2013 Data Capture DOE-LM (Westminster, CO); 

EMCBC (Denver, CO)

Initial Follow-up 

Actions

02/22/2013 Data Capture OSTI (Oak Ridge, TN)

Initial Follow-up 

Actions

02/25/2013 Secure Discussions NIOSH (Cincinnati, OH)

Secondary Follow-up 

Actions

05/30/2013 Reconstructing Rocky Flats Tritium 

Doses Pre- and Post-1973 (see 

Appendix 1)

ORAUT (Cincinnati, OH)

Secondary Follow-up 

Actions

03/06/2014 Response to WG/SC&A Comments on 

the RFP Tritium White Paper (see 

Appendix 2)

NIOSH (Cincinnati, OH); 

prepared by ORAUT 

(Cincinnati, OH)

Secondary Follow-up 

Actions

05/13/2015 Workplace Air Tritium Monitoring at 

Rocky Flats, 1977-1981 (see Appendix 

3)

ORAUT (Cincinnati, OH)
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 11 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Category Type Date Activity or Paper Title Location

Secondary Follow-up 

Actions

11/16/2015 Revision of the 1973 and later tritium 

dose assessment and dose assignments 

(see Appendix 1, Part II)

ORAUT (Cincinnati, OH)

As indicated in Table 2 above, DOE-EMCBC (Denver), LANL (Los Alamos), and OSTI (Oak 

Ridge) are sites where reviews of classified material were performed. Secure interviews were 

conducted at DOE-EMCBC.

Table 3: Follow-up Interviews Performed in Support of SEC-00192

Site Interview Topic Interview Date SRDB Ref ID

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/6/2012 122515

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/6/2012 122553

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/6/2012 122666

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/6/2012 122667

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/6/2012 122668

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/6/2012 122551

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/6/2012 122550

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/7/2012 122517

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/7/2012 122516
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Site Interview Topic Interview Date SRDB Ref ID

Rocky Flats, SEC-00192 Tritium 

(secure interview 

conducted at Denver 

Federal Center)

11/7/2012 122669

Rocky Flats, SEC-00192 Tritium Building 123 1/15/2013 122627

Rocky Flats, SEC-00192 Tritium Building 123 1/15/2013 122628

Rocky Flats, SEC-00192 Tritium Building 123 1/16/2013 122624

Rocky Flats, SEC-00192 Tritium Building 123 1/18/2013 122625

Rocky Flats, SEC-00192 Tritium Building 123 1/22/2013 122629

Rocky Flats, SEC-00192 Tritium Building 123 1/22/2013 122623

Rocky Flats, SEC-00192 Tritium Building 123 1/23/2013 122626

Rocky Flats, SEC-00192 Tritium Building 123 1/31/2013 122670

Rocky Flats, SEC-00192 Tritium Building 123 1/31/2013 122671
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 13 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Appendix 1: Reconstructing Rocky Flats Tritium 

Doses Pre- and Post-1973

J. S. Bogard, E. M. Brackett, and Mutty Sharfi, ORAUT 

Introduction

The potential for tritium exposure to Rocky Flats personnel was not considered significant until 

an unexpected release occurred in April 1973. Because tritium monitoring was not rigorous 

before this event, NIOSH requested that ORAUT perform a follow-up effort to validate the 

tritium bounding method for the SEC-00192 RFP ER, which uses information from the 1973 

tritium incident as the maximum exposure scenario. ORAUT conducted additional document 

data captures and personnel interviews regarding the existence of tritium on site and associated 

personnel exposures as well as follow-up on tritium bubbler sampling, shipping container tritium 

surveys, and sampling analysis performed in Building 123. 

In light of the additional information and data gathered during the follow-up effort, NIOSH 

requested that ORAUT evaluate the available documentation and data to: (1) analyze RFP 

tritium exposures for 1959-1973; (2) determine the best approach for dose assignment for 1973 

and later; and then (3) produce an example tritium dose reconstruction employing the best 

approach determined in this analysis. This white paper presents the results of these three efforts: 

• Part I: Analysis of Rocky Flats Tritium Exposures for 1959-1973, by J. S. Bogard 

• Part II: Rocky Flats Tritium Dose Assignment for 1973 and Later by E. M. Brackett; 

Attachment A: Rocky Flats 1973 H-3 Dose Assignment by Tom LaBone, Nancy Chalmers, 

and E. M. Brackett

• Part III: Example RFP Tritium Dose Reconstruction by Mutty Sharfi
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 14 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

PART I of Appendix 1: Analysis of Rocky Flats Plant Tritium Exposures for 1959-1973 

J. S. Bogard, ORAUT 

Tritium Monitoring Data Prior to 1973 

Although tritium was used as a boost gas in weapons and as target material in neutron 

generators, it was not processed or handled in any significant quantities at Rocky Flats. Tritium 

was monitored in the environment around the site for a time, but that monitoring ceased and was 

left to the State of Colorado for a brief period preceding an environmental release that occurred 

in April 1973. No analytical records have been captured by NIOSH that might help establish the 

Rocky Flats workplace tritium environment prior to that time.

The management of Rocky Flats woke abruptly to the potential for tritium workplace and 

environmental contamination with the release in April 1973 of 500 Ci - 2,000 Ci of tritium, 

primarily from Building 779A, and its eventual detection in waters draining into a reservoir 

serving as a municipal drinking water supply (SRDB 110941; 111269; 111284). The release 

also resulted in tritium exposure to a small number of Rocky Flats personnel. Subsequent 

workplace monitoring and personnel bioassay was implemented, in part to establish the baseline 

tritium environment against which future incidents could be evaluated. A smaller and lessimpactful tritium release occurred in September 1974 from Building 777; the subsequent 

investigation report (SRDB 8790) includes release details along with summaries of tritium 

workplace monitoring results prior to the incident for comparison. These data provide the basis 

for a model for bounding chronic tritium exposures to workers and of smaller, less-notable 

tritium releases that might have occurred prior to 1973.

Several factors single out the 1973 tritium release as bounding for the entire history of Rocky 

Flats operations. These factors include the large quantity of tritium involved, the chemical form 

of the released tritium, and the meteorological conditions at the time of the release. Other 

documented releases involved smaller quantities of elemental tritium, having a much smaller 

dose conversion factor than the tritium oxide released in 1973. Bounds for personnel tritium 

exposures after the 1973 release can be developed based on measurement results, since personnel 

bioassay, air sampling, and workplace contamination monitoring for tritium became more 

common after that release. There are only very limited tritium measurement results prior to 1973 

because tritium was not perceived as a radionuclide of occupational or environmental interest at 

Rocky Flats. Methods for bounding tritium exposures for the pre-1973 period are more difficult 

to develop as a result of this lack of measurement data.

According to a ChemRisk report (SRDB 8017), there was no environmental monitoring for 

tritium prior to 1970, and little in the way of workplace monitoring until after the 1973 tritium 

release; therefore, evidence of tritium releases prior to 1973 is primarily anecdotal. A 600-Ci 

release of elemental tritium (from a different source than the 1973 release) occurred in 1968. 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 15 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

The ChemRisk report said the following with regard to possible releases from tritiated Pu 

shipments (SRDB 8017, PDF p. 285): 

The 1973 findings associated with the tritiated plutonium initiated an 

investigation of other possible similar shipments and processing of tritiated 

plutonium. The investigation discovered three other shipments with maximum 

estimated tritium releases of 57 Ci (April 1969), 40 Ci (March 1971), and 29 Ci 

(November 1971). 

The reported investigation and the documented 1968 release of elemental tritium are the only 

sources of information about other possible releases. The 1968 release was elemental tritium 

with no significant environmental or personnel exposure. None of the three identified potential 

releases from tritiated Pu was near the magnitude of the 1973 release. There is no evidence of a 

tritium release comparable to the magnitude and impact of the 1973 release prior to that year. 

Source of Data for the Pre-1973 Period 

Despite the lack of measurement data, it is possible to develop pre-1973 tritium exposure bounds 

based on measurement results provided in a Rocky Flats Area Office (RFAO) report issued 

subsequent to a tritium release in one of the Rocky Flats production buildings on August 30, 

1974 (SRDB 8790). The information contained in this report includes measurement data (i.e., 

results from air samples, surface contamination surveys, and bioassay) from the production area 

where the release occurred as well as comparison data from other areas prior to, during, and after 

the release. Several factors support the use of these data as surrogates for bounding the tritium 

environment at Rocky Flats prior to 1973. They include the following: 

• Background tritium levels immediately prior to the incident described in the RFAO report, 

although undoubtedly elevated since the more significant 1973 release, were well below 

dosimetrically-significant values and can be considered as fairly representative of typical 

background levels for this analysis. The background tritium levels monitored in the months 

prior to the 1974 incident are consistent with internal radiation doses from tritium of well 

under 1 mrem annually. They are dosimetrically insignificant in this sense. 

• The quantity of tritium released (1.5 Ci) was significantly less than that released in 1973, and 

is probably more typical of potential undocumented releases in work areas – particularly 

those resulting from opening contaminated shipping containers. 

The 1974 1.5-Ci tritium release is the only documented release from a shipping container in 

the Rocky Flats workplace. It is taken to be typical since there are no other such documented 

releases to use in forming the model. There is documented concern about tritium releases, as 

shown in the following quote from the ChemRisk report (SDRB 8017, PDF p.38): 

As early as 1962, Rocky Flats maintained instruments for detection of tritium gas in 

particular work areas of the plant because operations have sometimes resulted in the 

storage of tritium containers. 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 16 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

The instruments available to Rocky Flats at that time were only semi-quantitative for 

indicating the presence of tritium; NIOSH has captured no records of these results. 

Because NIOSH has only identified six documented releases from 1968-1974 (an average of 

1 per year), the application of a daily release would be a significant/bounding overestimate of 

the number of RFP tritium releases.

• Tritium was released to the workplace environment, and not in a glovebox. 

• The release involved elemental tritium (HT, T2), and not tritium oxide (HTO).1

1 The impact of the 1973 tritium release was largely due both to the quantity (500 Ci – 2,000 Ci) and the chemical form (HTO) of 

the material. The presence of tritium oxide in the 1973 release resulted from peculiarities of the plutonium recovery operation 

from which it was generated. There is no indication that any other tritium release at Rocky Flats involved the oxide. Tritium in its 

elemental form (HT, T2) is far more likely to have been a contaminant at Rocky Flats because of the nature of its possible source 

terms – tritiated accelerator targets (neutron generators), plutonium hydride in recovery operations, and boost gas in returned 

reservoirs or pits.

• The tritium was released from a contaminated shipping container which was procured by 

Rocky Flats in 1970 and can be taken as representative of shipping containers in use prior to 

1973. 

As stated in the response to Item 2, the 1974 1.5-Ci tritium release is the only documented

release from a shipping container in the Rocky Flats workplace. It is taken to be typical since 

there are no other such documented releases to use in forming the model. There is 

documented concern about such releases, as shown in the following quote from the 

ChemRisk report (SDRB 8017, PDF p.38): 

As early as 1962, Rocky Flats maintained instruments for detection of tritium gas in 

particular work areas of the plant because operations have sometimes resulted in the 

storage of tritium containers. 

The instruments available to Rocky Flats at that time were only semi-quantitative for 

indicating the presence of tritium; NIOSH has captured no records of these results. Because 

NIOSH has only identified six documented releases from 1968-1974 (an average of 1 per 

year), the application of a daily release would be a significant/bounding overestimate of the 

number of RFP tritium releases.

• The incident occurred close enough in time to the 1973 tritium release that work practices 

and controls were likely more similar to those prior to 1973 than to those even a year or two 

later, as procedures and controls evolved with greater sensitivity to the potential for tritium 

contamination. 

The RFAO report provides the best source of monitoring data for use in bounding both chronic 

and accidental tritium exposures to Rocky Flats personnel prior to the unique circumstances of 

the 1973 release. The RFAO report states that elevated tritium concentrations were detected in 

 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 17 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

air samples from Room 452 (Special Assembly Area) in Building 777 and from the Building 205 

exhaust plenum servicing Building 776/777 over the period of August 29 – September 4, 1974 

(SRDB 8790, PDF p.9). Subsequent sampling and investigation of the elevated sample results 

concluded that about 1.5 Ci of tritium was released from the exhaust system of Room 452, 

Building 777, when a shipping container (referred to as a “pressure cooker”) received in July 

1974 from Battelle Pacific Northwest Laboratory (BNW) was opened on a downdraft table in 

Room 452 on August 30 (SRDB 8790, PDF pp. 36-39). No elevated environmental tritium 

levels were detected as a result of the incident, but workplace tritium levels seven times the 

applicable Radiological Control Guide were detected in air samples collected on August 30 in 

Room 452 adjacent to the downdraft table, with average concentrations for the work week about 

1.5 times the guidelines. Table A1-1 below shows the reported values. 

Table A1-1: Reported Tritium Air Concentrations (μCi/m3) from the August 30, 1974 Release

Sampling Reference Plenum 205, Bldg. 776/777a Room 452, Bldg. 777

Normal Concentrations <1×10 2 <1×10 2

August 29-30, 1974 0.148 37.7

September 3-4, 1974 2.51 1.1

Source: SRDB Ref ID: 8790, PDF pp. 93-96 a The Special Assembly Glovebox Line in Room 452, Building 777, was normally served by Plenum 206, but exhaust air from 

this area was vented through Plenum 205 from February 11 – August 7, 1974, while a new Plenum 206 was constructed. A 

tritium air sampler for Plenum 206 was installed on August 30, 1974, but showed no elevated results. However, both Plenum 

205 and Plenum 206 showed elevated tritium removable contamination (SRDB 8790, PDF pp.74-82).

An air sampler located near the downdraft table in Room 452 indicated a tritium air 

concentration of 4.9×10-3 μCi/m3 on August 29 and 37.7 μCi/m3 on August 30. The applicable 

Radioactive Concentration Guideline at the time was 5 μCi/m3

. Two “pressure cookers” were 

opened at the downdraft table, coincident with the elevated tritium-in-air measurements, and 

were smear-sampled for removable tritium contamination. One cooker showed smear levels of 

1.16×10-2 μCi; the other showed 3.43×102 μCi and was presumed to be the source of the gaseous 

tritium release.

Air Sample Results

Results from air samples collected daily in Room 452, Building 777, are available from June 3 to 

September 11, 1974. The air sampler was located near the downdraft table entry to the Special 

Assembly Line where the tritium contaminated “pressure cooker” was opened and was the only 

tritium air sampler in Building 777 at the time. Room air samples were collected in a water 

bubbler during the day shift (approximately 6 or 8 hours sampling time) at an air flow rate of 

2 L/min. Individual results are shown in Table A1-2 below (SRDB: 8790, PDF pp. 87-89).
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 18 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Table A1-2: Tritium Activity Concentrations in Room Air: Rm. 452 - Special Assembly - Bldg. 777

Analysis Date (1974) [

3

H] (pCi/m3)

3-June 9,428

5-June 12,121

4-June 20,370

6-June 16,498

7-June 5,892

11-June 13,972

11-June 10,894

12-June 12,358

13-June 4,553

14-June 5,387

17-June 6,829

18-June 5,781

19-June 4,414

20-June 4,553

21-June 4,348

24-June No recorded value

25-June No recorded value

26-June 4,519

27-June 5,366

27-June 4,553

1-July 4,348

2-July 3,454

3-July 4,655

5-July 3,030

8-July 3,872

9-July 2,512

10-July 2,602

11-July 4,553

15-July 6,742

16-July 5,040

17-July 21,022

18-July 4,209

19-July 5,041

22-July 4,866

23-July 4,866

24-July 1,010

25-July 3,089

26-July 2,118

29-July 2,512

30-July 1,727

1-August 1,842

1-August 2,269

5-August 2,512

7-August 1,179

8-August 628

12-August 1,256
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 19 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Analysis Date (1974) [

3

H] (pCi/m3)

13-August 1,301

16-August No recorded value

20-August 2,439

21-August 3,140

22-August 3,298

23-August No recorded value

26-August 2,927

27-August 3,089

28-August 4,874

29-August 3,986

30-August 37,676,609

3-September 1,098,901

4-September 8,477

5-September 5,108

6-September No recorded value

9-September 3,030

10-September 3,140

11-September 2,898

Source: SRDB Ref ID: 8790, PDF pp. 87-89

The average and standard deviation of daily air sample results prior to August 30, the day of the 

tritium release from the contaminated shipping container, are (5343 ± 4518) pCi/m3

. The result 

on August 30 is 37,676,609 pCi/m3, and the sample taken on September 3 indicated a tritium 

concentration in the room air of 1,098,901 pCi/m3

. However, the September 3 result is suspect 

because the sample was collected in the same vessel that was used on August 30 and which had 

not been cleaned. Smear surveys of Room 452 on September 3 failed to show significant tritium 

contamination (SRDB 8790, PDF pp.37-38). Tritium levels in Building 777 were known to be 

somewhat elevated over normal background because of residual contamination present since the 

1973 tritium release. 

Bioassay Results

The practice of pulling a sample of air from within shipping containers through a tritium air 

monitor to check for contamination was implemented after the 1973 tritium release. This 

practice was discontinued after urinary tritium results in the range of 0.75 μCi/L – 1.3 μCi/L 

were detected in May 1974 for the health physics technician who performed the monitoring. The 

technician’s urinary tritium dropped to less than 0.1 μCi/L beginning in early July 1974 (SRDB 

8790, PDF pp. 18-19).

All employees who worked in Room 452, Building 777, submitted urine samples after the 

August 30 tritium release, with a high result of 32,320 pCi/L. Table A1-3 below shows 

individual results (SRDB 8790, PDF p. 90).
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 20 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Table A1-3: Tritium Urinalysis Results for Exposed Workers and Others, August 30, 1974

Worker ID Area Urinary Tritium 

(pCi/L) Uncertainty (pCi/L)

510 777 32320 ± 6170

869 777 25610 ± 6100

180 779 24000 Value not provided

548 777 22370 ± 5800

12 777 21600 ± 5800

112 707 17000 Value not provided

998 777 15740 ± 6100

680 777 15730 ± 5640

449 779 14000 Value not provided

801 707 13700 ± 5370

004 123 630 ± 580

Non-Occupational 

(Denver)

Non-Occupational 

(Denver) 470 Value not provided

Source: SRDB Ref ID: 8790, PDF p. 90

The report indicates that both a Denver resident and a Dow employee who did not work in 

radioactive material-handling areas were sampled with results < 0.01 μCi/L (<10,000 pCi/L). 

The Denver resident is identified in Table A1-3, and Worker ID 004 is believed, by implication, 

to be the Dow non-radiological worker.

Work Area Smear Surveys

Over 200 smear results for tritium are tabulated in the RFAO report (SRDB 8790, PDF pp. 74-

82). Most appear to be surveys inside glove boxes, but there are also workplace area results that 

can be used as indicators of likely sources of internal contamination of workers following an 

event such as the one in August 1974. The workplace smear results are shown in Table A1-4 

below.

Table A1-4: Tritium Smear Surveys – Work Areas in Buildings 776-777

Date Bldg./Room Location Maximum Smear (pCi)

9/6/74 776-205 205 Plenum - cold side < 100

9/6/74 776-206 206 Plenum - cold side < 100

9/6/74 777-452 206-532 - top of box < 100

9/6/74 777-430 E.S. Welder 353,000

9/6/74 777-437 Penthouse < 100

9/6/74 777-437 A-1 110,000

9/6/74 777-437 A-2 4,800
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 21 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Date Bldg./Room Location Maximum Smear (pCi)

9/6/74 777-437 A-3 9,400

9/6/74 777-463 A-5 1,200

9/6/74 777-463 Conveyor Line 7,900

9/6/74 777-463 A-7 7,700

9/9/74 776-205 205 Plenum (hot side) 211,000

9/9/74 776-206 206 Plenum (hot side) 1,230,000

9/10/74 776 - Size Reduction Floor < 500

9/10/74 776-201 Floor 1,100

9/11/74 777-452 Floor at J-24 460

9/11/74 777-452 Floor at K-24 470

9/11/74 777-452 Floor at L-24 640

9/11/74 777-452 Floor at M-24 780

9/11/74 777-452 Floor at K-25 560

9/11/74 777-452 Floor at J-25 950

9/11/74 776-250 Plenum Floor < 100

9/11/74 776-250 Plenum Fan < 100

9/11/74 776-252 Plenum Floor 465

9/11/74 776-252 Plenum Filter 1,636

9/11/74 776-S-8 Plenum Filter < 100

9/11/74 776-S-8 Plenum Deep Beds < 100

9/11/74 776-S-7 Plenum Filter < 100

9/11/74 776-S-7 Plenum Floor < 100

9/11/74 776-S-4 Plenum Filter < 100

9/11/74 776-251 Plenum Floor 3,625

9/11/74 776-251 Plenum Filter 3,603

9/11/74 776-440 Floor 1,000

9/11/74 776-432 Floor K-20 500

9/11/74 776-432 Floor H-19 1,460

9/11/74 776-432 Floor H-20 710

9/11/74 776-432 Floor K-19 520

9/11/74 776-201 #1 System Kathene 160,000

9/11/74 776-201 #4 System Kathene 400,000

9/11/74 776-201 #3/7 System Kathene 450,000

9/11/74 776-201 #8 System Kathene 140,000

9/11/74 776-201 GBDA System Kathene 400,000

Source: SRDB 8790, PDF pp. 74-82
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 22 of 45

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

The exhaust plenums and the Kathabar air driers (which use a lithium chloride solution called 

Kathene) appear to have collected the greatest amount of tritium after the release. Workers 

responsible for changing filters in the plenums or recharging the Kathabar systems would appear 

to be at greatest risk for tritium uptake after the initial release.

Assessment of the 1974 Incident

The 1.5-Ci tritium release from a contaminated shipping container occurred on August 30, 1974. 

The RFAO report provides air survey, bioassay, and smear survey results (SRDB 8790). 

Specific urine sample collection dates were not included in the report but data were matched to 

two NOCTS claims, which reported a collection date of September 5, 1974. A dose assessment 

was performed using the Integrated Modules for Bioassay Analysis (IMBA) software. An intake 

date of August 30, 1974, was assumed and the largest reported result collected after the incident, 

36,320 pCi/L, was used. There was a slight discrepancy (one digit) between the result included 

in the RFAO report and that in the NOCTS case file. The NOCTS value is assumed to be correct 

because it is the handwritten urinalysis record and is also the larger of the two values. The 

resulting dose is < 1 mrem (0.15 mrem). The Excel file RFP H-3 dose calculations – data.xlsx 

contains the information above as well as the data used for the analysis.

Conclusion

The RFAO report (SRDB 8790) of a 1.5-Ci tritium release on August 30, 1974 from a 

contaminated shipping container (“pressure cooker”) provides air survey, bioassay, and smear 

survey results that can be used to model similar releases. Such a model can be scaled to account 

for the source term and applied to incidents prior to the 1973 environmental tritium release when 

such tritium monitoring data are not available for Rocky Flats. The baseline information from 

these data can also be used to model the pre-1973 background tritium environment at Rocky 

Flats because the 1974 release described in the RFAO report occurred close enough in time to 

the seminal 1973 tritium event that many or most of the procedures and workplace practices had 

only begun to transition to account for the new sensitivity to tritium and its potential impact on 

Rocky Flats operations.

The number and nature of reported tritium release events, both before and after 1973, provide the 

basis for assumptions of pre-1973 workplace release frequencies, quantities, and chemical forms. 

The parameters of this model can then be used to estimate pre-1973 bounding doses to Rocky 

Flats workers from estimates of the tritium background environment and tritium release 

incidents, particularly those involving contaminated shipping containers.
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 23 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

PART II of Appendix 1: Rocky Flats Tritium Dose Assignment for 1973 and Later

E. M. Brackett, ORAUT

Revised: November 16, 2015

Dose Assignment for 1973

The report, Investigation of the Tritium Release Occurrence at the Rocky Flats Plant (SRDB 

24165, PDF p. 16), describes a 1973 incident that prompted the site to sample a number of 

workers for tritium exposure. A shipment of scrap plutonium from LLNL was discovered to 

have been contaminated with tritium. This material was processed at the Rocky Flats Plant from 

April 9-25, 1973 in Building 779A. Because it was not immediately identified as being 

contaminated, monitoring of potentially exposed individuals did not begin until late September 

1973.

Two-hundred-fifty people were sampled following the discovery; this included all employees 

who worked in areas in which the contaminated scrap was processed or who were involved in the 

processing of wastes from this scrap. Due to the large sample load, raw urine samples were first 

analyzed in many of the cases. It was noted that the counting efficiency was only about 3% for 

these analyses, and that the corrections made for spectral shift could lead to abnormally high 

readings. Nineteen employees were initially identified as having elevated tritium levels in their 

urine. These samples were distilled and re-analyzed. Upon this re-check, fourteen of these 

employees were found to be below the 10,000 pCi/L action level established by the site. The 

five most-exposed individuals were identified and details of their potential exposures, including 

bioassay results, are included in the above-cited investigation report. One of these five 

individuals is in NOCTS. 

Tritium contamination was associated with plutonium scrap material; therefore, H-3 doses will 

be assigned to all individuals who were monitored for plutonium in 1973. Doses will be 

assessed on an individual basis using reported H-3 bioassay results and any additional 

information in the NOCTS file. For those who were not monitored for H-3, dose will be 

assigned based on claimant-favorable assumptions.

The tritium release incident report (SRDB 24165) discusses the tritium sampling of 250 people 

as of October 15, 1973. There are no results or specific sample dates given in the report for 

those individuals who did not exceed the H-3 bioassay follow-up action level of 10,000 pCi/L. 

Only five individuals were found to have results exceeding the action level so this current 

assessment assumes that they are the maximally-exposed workers in the incident and that those 

who were not monitored would not have been exposed at those same levels. After discussions 

regarding the tritium model at the RFP Board Working Group meeting, NIOSH decided to adopt 

the use of the tritium model described in Review of the ICRP Tritium and C-14 Internal 

Dosimetry Models and Their Implementation in the GENMOD-PC Code by R. B. Richardson 

and D. W. Dunford, for this assessment.
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Based on this information, the following assumptions were applied: 

• H-3 was in the form of tritiated water (HTO)

• Model for inorganic H-3, as described in Review of the ICRP Tritium and C-14 Internal 

Dosimetry Models and Their Implementation in the GENMOD-PC Code by R. B. Richardson 

and D. W. Dunford (Health Physics 81(3):289 –301; 2001) 

• Mode of intake was injection (for modeling with IMBA) 

• Intake date = April 9, 1973 (first day the material was processed) 

• Sample collected on October 15, 1973 

• Result = 10,000 pCi/L (14,000 pCi/day) 

Using this information, the total dose is 103 mrem. Attachment A contains details and 

justification for the model.

Dose Assignment for 1974-1975 

ORAUT performed a co-worker study using data from NOCTS for 1974 and 1975. There are 38 

individuals with tritium data in 1974 and 37 in 1975. ORAUT-OTIB-0075, Use of Claimant 

Datasets for Coworker Modeling, provides justification and guidance. 

When assessing tritium intakes for most sites, it is assumed that intake potential exists only while 

tritium bioassay monitoring is being performed because monitoring is cheap, easy, and requires 

only spot samples, thus presenting less of a burden than other forms of bioassay on both the 

employer and the employee. Because tritium was not of primary concern at RFP and was 

present only as a potential contaminant on equipment, a given individual was not placed on a 

routine sampling program. Instead, a program was established whereby one-tenth of the urine 

samples collected for plutonium analysis were also analyzed for tritium content (SRDB 111267, 

letter from RFP General Manager to RFAO AEC Manager) as well as the collection of samples 

when a particular concern was identified. Samples available in NOCTS for these two years 

indicate that analyses were performed throughout the year, with most individuals sampled only 

once.

For the purpose of the co-worker study, it was assumed that each worker had the potential to be 

exposed at a constant level throughout the year in which the urine sample was collected. The 

95th percentile was used because one-tenth of the population was sampled. The co-worker study 

for 1974-1975 yielded doses of much less than 1 mrem for everyone. The file, Tritium for 1974-

1975 coworker.xlsx, contains the assumptions employed in the study. 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Dose Assignment After 1975

For the post-1975 years, there are 11 or fewer individuals in NOCTS with tritium data; this is 

insufficient for performing a co-worker study. Results for these years are consistent with those 

from the previous years and show a general decreasing personnel exposure trend. The dose from 

the 1974-1975 co-worker study (i.e., 0 mrem - see above) will apply to these years; therefore, no 

additional dose due to tritium, as it relates to the assessment performed in this analysis, will be 

assigned after 1973 at RFP.
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Attachment A: Tritiated Water Models

Thomas LaBone, Nancy Chalmers, and E. M. Brackett, ORAUT 

Purpose 

Calculate urinary excretion following an acute uptake of "stable" HTO using the ICRP 68 

biokinetic model, as interpreted by Dunford in GENMOD. 

Define Biokinetic Model for HTO

TOL 10− 5 ≡

ORIGIN ≡ 1

xfer ≡ 1 bladder ≡ 4

tbA ≡ 2 urine ≡ 5

tbB ≡ 3 other ≡ 6

Define Transfer and Total Removal Rate Constants 

k

xfer, tbA

0.97

ln 2( )

0.25⋅day

:= ⋅ k

tbA, bladder

1.4

3.0

ln 2( )

10⋅day

:= ⋅

k

xfer, tbB

0.03

ln 2( )

0.25⋅day

:= ⋅ k

tbA, other

1.6

3.0

ln 2( )

10⋅day

:= ⋅

k

tbB, bladder 0.47

ln 2( )

40⋅day

:= ⋅ kbladder urine , 12 day− 1

:= ⋅

k

tbB, other 0.53

ln 2( )

40⋅day

:= ⋅

k

xfer xfer , kxfer, tbA

k

xfer, tbB

+ ( ) := − kbladder bladder , kbladder urine , := −

k

tbA, tbA

k

tbA, bladder ktbA, other + ( ) := − k

urine urine , := 0

k

tbB, tbB

k

tbB, bladder ktbB, other + ( ) := − k

other other , := 0

q0other := 0

Note that the initial contents are expressed in terms of atoms, which have no dimensions or units.

q0xfer := 1.0
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information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Calculate Eigensystem (es) and Define Retention Functions

γ eigenvals k

T

:= ( )

V eigenvecs k

T

:= ( )

c V− 1

:= ⋅q0

j := xfer.. other

Cj c

j Vurine j , := ⋅

Cumulative Urine Function

qu t( )

xfer

other

j

Cj exp γ j ⋅ ( ) ⋅t ∑ ( ) =

:=

24-hour Incremental Urine Function

∆eu t( ) qu t( ) qu := ( − ( ) t 1⋅− day )

Instantaneous Urine Function (units of 1/time)

dqu t( )

xfer

other

j

γ j Cj ⋅ exp γ j ⋅ ( ) ⋅t ∑ ( ) =

:=

Stable Element Examples

t := 191⋅day

qu t( ) 4.662 10− 1 ×=

∆eu t( ) 9.131 10− 6 ×=

dqu t( ) 9.051 10− 6 × day− 1 =

Adjusting for Radioactive Decay to Show How it is Done

λ ln 2( )

4485⋅day

:=

∆eu t( )⋅exp( ) λ− ⋅t 8.866 10− 6 ×=
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

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ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Coefficients and Rate Constants for IMBA Bioassay Mode 

γi Ci ⋅

0.0000000000·100

0.0000000000·100

9.5560778736·10-3

3.2367951670·10-2

2.4622664058·10-4

-4.2170256184·10-2

day− 1

= γi

0.0000000000·100

0.0000000000·100

-1.2000000000·101

-6.9314718056·10-2

-1.7328679514·10-2

-2.7725887222·100

day− 1

=

References for Part II, Attachment A

A general discussion of solving differential equations describing biokinetic systems: 

Jacquez, J. A., Compartmental Analysis in Biology and Medicine (Ann Arbor: University of 

Michigan Press) 1985. 

Using eigenvalues to solve differential equations: 

Killough, G. G., Eckerman, K. F., A Conversational Eigenanalysis Program for Solving 

Differential Equations, in Computer Applications in Health Physics, Proceedings of the 

Seventeenth Midyear Topical Symposium of the Health Physics Society, 1984.

E. Polig, Modeling the Distribution and Dosimetry of Internal Emitters: A Review of 

Mathematical Procedures Using Matrix Methods; Health Physics (81)5:492-501; 2001. 

ICRP 68 Tritium Biokinetic Model: 

R. B. Richardson and D. W. Dunford, Review of the ICRP Tritium and C-14 Internal Dosimetry 

Models and Their Implementation in the GENMOD-PC Code, Health Physics 81(3):289 –301; 

2001. 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

PART III of Appendix 1: Example RFP Tritium Dose Reconstruction 

Mutty Sharfi, ORAUT

Employee Information 

Cancer Description: Lung (ICD-9: 162); diagnosed 12/31/2000 

Prostate (ICD-9: 185); diagnosed 12/31/2000 

BCC (ICD-9: 173); diagnosed 12/31/2000 

SCC (ICD-9: 173); diagnosed 12/31/2000 

Year of birth: 1932 

Gender: Male

Smoking: Never Smoked

Ethnicity: “White, non-Hispanic”

Employment Information 

Start date: 01/01/1959 

End date: 12/31/1975 

Occupation: Unknown 

Dosimetry Data: None 

Organ Dose Assessed

Table A1-5: Organ Dose Assessed

Cancer External Organ Used Internal Organ Used

Lung Lung Lung

Prostate Urinary Bladder

Heart Wall

(non-metabolic organ with 

the highest dose)

Skin Skin Skin

Source: ORAUT-OTIB-0005

External Dose 

Not applicable for tritium exposures.
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Internal Dose

Pre-1973

The 1.5-Ci tritium release from a contaminated shipping container occurred on August 30, 1974. 

The largest reported bioassay result (SRDB 8790) collected after the incident was used to assess 

the potential exposure from this release. The resulting dose is was about 0.15 mrem. Assuming 

this event occurred every workday of the year (250 times a year), the resulting annual dose 

would be about 37.5 mrem/year. This will be used as a bounding estimate for all workers’ 

potential tritium exposure prior to 1973.

1973

The report, Investigation of the Tritium Release Occurrence at the Rocky Flats Plant (SRDB 

24165, PDF p. 16), describes a 1973 incident that prompted the site to sample a number of 

workers for tritium exposure. A shipment of scrap plutonium from LLNL was discovered to 

have been contaminated with tritium. This material was processed at the Rocky Flats Plant from 

April 9 - 25, 1973 in Building 779A. Because it was not immediately identified as being 

contaminated, monitoring potentially exposed individuals did not begin until late September 

1973.

Two hundred fifty people were sampled following the discovery; this included all employees 

who worked in areas in which the contaminated scrap was processed, or who were involved in 

processing wastes from this scrap. In many of the cases, due to the large sample load, raw urine 

samples were first analyzed. It was noted that the counting efficiency was only about 3% for 

these analyses, and that the corrections made for spectral shift could lead to abnormally high 

readings. Nineteen employees were initially identified as having elevated tritium levels in their 

urine. These samples were distilled and re-analyzed. Upon this re-check, fourteen of these 

employees were found to be below the 10,000 pCi/L action level established by the site. The 

five most-exposed individuals were identified and details of their potential exposures, including 

bioassay results, are included in the investigation report. Results for one of these five individuals 

are included in NOCTS.

Tritium contamination was associated with plutonium scrap material; therefore, H-3 doses will 

be assigned to all individuals who were monitored for plutonium in 1973. Doses will be 

assessed on an individual basis using reported H-3 bioassay results and any additional 

information in the NOCTS file. For those who were not monitored for H-3, dose will be 

assigned based on claimant-favorable assumptions.

The incident report (SRDB 24165) says that 250 people were sampled as of October 15, 1973. 

There are no results or specific dates given, but an action level of 10,000 pCi/L was established 

for follow-up analysis. This value was used as the maximum result for those who were not 

monitored. Only five individuals were found to have results exceeding the action level, so it is 

assumed that those who were not monitored would not have been exposed at the same levels.
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Based on this information, the following assumptions were applied: 

• H-3 in the form of tritiated water (HTO).

• Model for inorganic H-3, as described for inorganic H-3, as described in Review of the ICRP 

Tritium and C-14 Internal Dosimetry Models and Their Implementation in the GENMOD-PC 

Code by R. B. Richardson and D. W. Dunford; Health Physics 81(3):289 –301; 2001.

• Injection intake (for modeling with IMBA).

• Intake date = April 9, 1973 (first day the material was processed). 

• Sample collected on October 15, 1973. 

• Result = 10,000 pCi/L (14,000 pCi/day). 

Using the above information, the total dose is 103 mrem. 

Post-1973 

A co-worker study was performed using data from NOCTS for 1974 and 1975. There are 38 

individuals with tritium data in 1974 and 37 in 1975. ORAUT-OTIB-0075, Use of Claimant 

Datasets for Coworker Modeling, provides justification and guidance. 

When assessing tritium intakes for most sites, it is assumed that intake potential exists only while 

tritium bioassay monitoring is being performed because monitoring is cheap, easy, and requires 

only spot samples, thus, presenting less of a burden than other forms of bioassay on both the 

employer and the employee. Because tritium was not of primary concern at RFP and was 

present only as a potential contaminant on equipment, a given individual was not placed on a 

routine sampling program. Instead, a program was established whereby one-tenth of the urine 

samples collected for plutonium analysis were also analyzed for tritium content (SRDB 111267, 

letter from RFP General Manager to RFAO AEC Manager) as well as the collection of samples 

when there was a particular concern. Samples available in NOCTS for these two years indicate 

that analyses were performed throughout the year, with most individuals sampled only once. 

For the purpose of the co-worker study, it was assumed that each worker had the potential to be 

exposed at a constant level throughout the year in which the urine sample was collected. The 

95th percentile was used because one-tenth of the population was sampled. The co-worker study 

for 1974 -1975 yielded doses of much less than 1 mrem for everyone. The file, Tritium for 1974-

1975 coworker.xlsx, contains the assumptions employed in the study. 

For later years, there are 11 or fewer individuals in NOCTS with tritium data; this is insufficient 

for performing a co-worker study. Results for these years are consistent with those from the 

previous years and show a general decreasing trend. The dose from the 1974-1975 co-worker 

study (i.e., 0 mrem - see above) will apply to these years. Therefore, no additional dose due to 

tritium, as it relates to the assessment performed in this analysis, will be assigned after 1973. 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

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information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Uncertainty

All doses are applied as a constant distribution.

Summary 

The assessment methods presented in this report define the methods by which a dose estimate 

can be determined for the evaluated worker class. These methods support NIOSH’s conclusion 

that the operationally-related internal dose for the evaluated worker class can be bounded. A 

summary of the doses and probability of causations are provided in Table A-8 below.

Table A1-6: Example RFP Tritium DR – Summary of Doses and Probabilities of Causation

Cancer External (rem) Internal (rem) Total (rem) Probability of Causation

Lung 0.000 0.628 0.628 4.07%

Prostate 0.000 0.628 0.628 1.48%

Skin BCC 0.000 0.628 0.628 3.38%

Skin SCC 0.000 0.628 0.628 0.48%
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ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

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information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Appendix 2: Response to Work Group/SC&A 

Comments on the Rocky Flats Plant Tritium White 

Paper

Timeline

7/2013 – Board Working Group Meeting – developed issues from the Working Group/SC&A 

review of the initial revision of the NIOSH-ORAUT tritium white paper that were responded to 

in the response to comments document. 

9/2013 – Board Working Group Meeting – the tritium white paper was reviewed and the three 

periods assessed in the white paper were discussed: 

• 1973 – Liz B. to send the WG and SC&A her IMBA files so that they may perform a 

comparative review of the proposed pre-1973 method. 

• Post-1973 (1974-1975) – WG/SC&A not in agreement at the meeting about the dose being 

less than 1 mrem.

• Pre-1973 – discussions about the applicability of the 1974 incident data for the pre-1973 

period. 

10/2013 – AB Meeting – although a SEC class is recommended that covers the time period in 

question related to the tritium exposure, additional confirmation/agreement to occur in regard to 

the partial DR method for tritium in the SEC period.

• Dr. Ziemer requested information on why the post-1973 co-worker model came up with 0 

dose when there was dose associated with the 1974 incident – ensure that the bioassay 

samples from the 1974 incident in a co-worker model.

1/2014 – The SC&A report titled: SC&A Review of Part II, Rocky Flats Tritium Dose 

Assignment for 1973, Attachment A, was provided as an additional review response to the 

NIOSH tritium white paper based on Working Group tasking. Included in the email response 

associated with this SC&A review was an indication that this tritium dose assignment review 

only focused on the 1973 period, and that SC&A was awaiting a response for the pre- and post1973 methodologies presented in the NIOSH white paper. 

5/2014 – NIOSH posted revision 1 of the tritium white paper to address Working Group and 

DCAS comments.
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positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

9/2014 – The SC&A report titled SC&A Response to NIOSH White Paper: Follow-up Efforts on 

SEC-00192 Rocky Flats Plant Tritium Issues, dated May 30, 2014, was issued as a review 

response to the revised NIOSH tritium white paper. 

3/2015 – AB Meeting was held discussing the revised NIOSH tritium white paper (revision 1) 

and the Working Group/SC&A review of the revision. 

7/2015 – NIOSH posted revision 2 (dated 7/1/15) of the tritium white paper to address Working 

Group comments on revision 1; AB Meeting (on 7/14/15) – NIOSH tritium white paper revision 

2 was discussed by the Working Group and additional/final review comments were provided. 

12/2016 – NIOSH completed revision 3 of the tritium white paper to address remaining Working 

Group comments on revision 2 regarding the 1973 tritium model. 

Comments and Responses

Comment 1: If bubbler data exist and can be compared, compare pre-1973 data to 1974 data. 

Response: Only environmental and stack effluent tritium results have been captured for Rocky 

Flats prior to 1973. No tritium bubbler data for RFP work areas have been found for the pre1974 period. However, additional SRDB searches identified workplace tritium results obtained 

in September-October 1973 using cold traps – part of the effort by Rocky Flats to identify the 

source of the 1973 environmental tritium release. These data may be useful for comparison with 

the 1974 bubbler data, but they still represent results from work areas potentially affected by the 

April 1973 release. (See information in Comment 2 below.) 

Comment 2: Look at baseline survey data from 1973 (SRDB 68351) to see if comparisons can 

be made. NOTE: Recognize that bubbler data may be suspect based on a classified interview 

noting that the bubbler was only present during opening of the secondary container and not 

present when opening the primary container.

Response: In response to the working group discussion of the documents referenced in the white 

paper:

• SRDB Ref ID: 111095 is a collection of hand-written records of survey and air sample logs, 

including bubbler sample results (1121 pages). The document contains information for the 

years from 1977-1982. 

• SRDB Ref ID: 122712 is a collection of 1997 bubbler results analyzed and reported by 

Thermo NUtech (33 pages). There is no information in this source about other years at RFP. 

• SRDB Ref ID: 122550 is the official transcript of the NIOSH-ORAUT interview of a former 

RFP employee. The former employee indicates that RFP started using tritium bubblers when 

opening outer containers (not when opening inner containers containing the pits). This 

occurred in 1965 in the B771 downdraft room; however, no bubbler results for the period 
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information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

prior to 1973 have been found. The interviewee also indicated that the bubblers were 

positioned in front of the intake plenums of the exhaust systems to serve as alarming devices, 

and not to record routine airborne concentrations in the area. 

Based on additional research into the tritium release evaluation at RFP, ORAUT confirmed that 

smears, radioactive gas monitors, and cold traps were used in tracing the source of the April 

1973 release. However, the only workplace air monitoring results reported were from cold trap 

samples.

Radioactive gas monitor results were all from glove box atmospheres. SRDB Ref ID: 111284, 

PDF p.75, states (bold added for emphasis): 

A general survey using smear technique and subsequent radiochemical analysis at 

Building 123 was initiated in all buildings or specific areas of those buildings where the 

possibility of tritium was suspected. Smears were also taken inside glovebox lines in several 

areas. Most of the analysis for the latter group of smears has not been completed. In 

addition, air was monitored using Johnson Model 1055 or 955 radioactive gas monitors 

and/or cold trap samplers in Buildings 774 and 779-A. A bubbler sampler was installed to 

sample the Building 779-A exhaust air effluent and analysis for tritium was performed on 

water traps normally used as part of the stack sampler system for the Building 774 

evaporator stack. 

Table A2-1 summarizes the cold trap sample data presented on PDF p.79 in SRDB Ref ID: 

111284. 

Table A2-1: RFP Cold Trap Samples - Air

Building Room Date H-3 (pCi/m3) Remarks

774 203 9-28-73 20.7 none

774 220 9-28-73 9.2 none

774 210 10-1-73 14 none

774 320 10-1-73 15 none

779-A 154, NE 9-26-73 1,580 none

779-A 154, NE 9-28-73 10,000 none

779-A 154, NE 10-1-73 1,068 none

779-A 154, NE 10-2-73 451 none

779-A 154, NE 10-4-73 302 none

779-A 154, SW 9-26-73 1,491 none

779-A 154, SW 10-1-73 400,750 none

779-A 154, SW 10-2-73 113 none

779-A 154, SW 10-4-73 5,540 none

779-A 001 10-4-73 3,700 Sampling from above liquid level in building 

process holding tanks.

779-A 142 10-4-73 12,146

Boiler ventilation room. Filtered air passes 

through room and is recycled back to dryers and 

laboratories.
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

NOTE: The average and standard deviation of the above results are: 

• Building 774: (14.7 ± 4.7) pCi/m3

• Building 779-A, Rm 154 NE and SW: The documentation offers no explanation for the high 

result of 400,750 pCi/m3 on October 1, 1973. 

o Calculation including the high value: (46,810 ± 132,766) pCi/m3 

o Calculation excluding the high value: (2568 ± 3466) pCi/m3

Readings taken in Building 777, Rm 452 in the 31⁄2 months prior to the 1974 tritium 

contamination incident had average and standard deviation of (5343 ± 4518) pCi/m3

. 

Building 779-A, Rm 154 housed the glove box hydriding reaction chamber where tritiumcontaminated Pu from LLL was processed in April 1973, resulting in the highly-publicized 

environmental tritium release to public drinking water supply reservoirs. The resulting 

plutonium hydride was oxidized in other glove boxes in 779-A, Rm 154 before transfer to Bldg. 

771 for reduction to Pu metal. Bldg. 771 process wastes were then transferred to Bldg. 774 for 

further processing, or were sent either to the solar evaporation ponds or the sanitary sewer. 

Glove boxes in Building 779-A, Rm 154 and in Buildings 771 and 774 were all found to be 

contaminated with tritium after the 1973 environmental release. It is interesting to note that, 

even though Bldg. 774 glove boxes were tritium-contaminated, the Building 774 work area cold 

trap samples showed extremely low tritium results. It appears that the glove boxes provided 

good containment. 

ORAUT also reviewed the available NOCTS claims that had tritium bioassay data to determine 

the existence of a pre-1973 bioassay sampling program and to assess the sufficiency of the 

monitoring program for identifying potential tritium exposures and/or incidents. Five pre-1973 

tritium bioassay samples for five different individuals were identified out 312 total sample 

results for 125 individuals (data ranging from 1966-1996). The five pre-1973 tritium sample 

results are:

• Three urine samples, 1966: all background 

• One urine sample, January 1973: 5542 ± 846 (units not specified - assumption: pCi/L) 

• One urine sample, April 1973: background 

There do not appear to be any specific tritium incidents related to the collection of any of the pre1973 bioassay samples. However, the fact that the samples do exist indicates that there was a 

capability for tritium urinalysis and a will to use it going back to 1966. The result from January 

1973 is about 17% of the highest urine specimen from the 1974 incident, which supports the use 

of the 1974 data to bound the pre-1973 tritium doses. 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

To date, no information has been identified to dispute the use of the 1974 data in the 

development of a pre-1973 bounding approach for tritium at RFP. NIOSH-ORAUT will 

continue to assess the data to confirm that this continues to be the case and will address issues 

with the bounding approach if and when they arise. 

Comment 3: If the ChemRisk report is used for supporting dose reconstruction, look and see if 

the report was validated in any way.

Response: The ChemRisk report was referenced and used in the development of the RFP 

Environmental TBD. However, no additional validation of the report data has been performed 

by ORAUT. While this TBD may be used to support dose reconstructions, the exposure 

scenarios associated with the ChemRisk data are not considered to be representative of the most 

highly-exposed individuals (i.e., the data are more representative of radiological conditions 

outside of the work areas and plants). The available personnel monitoring/bioassay data 

contained in an individual’s personnel monitoring records are considered the most representative 

and bounding from a personnel exposure perspective. 

Comment 4: Determine whether Pantex changed their shipping controls/survey criteria/shipping 

survey and contamination limits (did they change?) after the 1973 tritium release at Rocky Flats. 

If so, when did any changes occur? 

Response: Based on the available documentation, it appears that the earliest changes made by 

Pantex that were related to tritium-contaminated shipments were made in the early 1980s. 

Below is a summary of the documentation review: 

Pantex: 

Based on the available documentation, it is not apparent that changes in the Pantex program in 

response to the 1973 or 1974 incidents (i.e., shipping controls/survey criteria/shipping survey 

and contamination limits) occurred until 1981 (SRDB 107801). Other Pantex documentation in 

the SRDB corroborates this conclusion (i.e., no available information is dated earlier than 1981) 

(SRDB 109244; 109245; 109246; 109255). 

RFP: 

The 1974 incident occurred on September 3-4, 1974. Five RFP documents in the SRDB relate to 

the post-1974 incident follow-up. These documents include: 

• SRDB 111267 (September 12, 1974) 

• SRDB 111288 (September 12-16, 1974) 

• SRDB 111301 (October 21, 1974) 

• SRDB 8789 (November 12, 1975) 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

• SRDB 111106 (December 1974) 

All these documents are related to the RFP’s post-incident responses, including: (1) 

implementation of RFP action levels; (2) RFP performance of tritium surveys of suspect 

shipments; and (3) RFP requests that sites shipping related packages to RFP perform their own 

surveys. 

A June 6, 1974, memorandum from Rocky Flats to the AEC indicates adoption of an upper limit 

of 10 mCi tritium per kilogram of plutonium shipped into Rocky Flats (SRDB 111268). 

Certification of an incoming material’s history was required of shippers in response to AEC 

recommendations (issued after the 1973 tritium release) leading to the realization that trace 

amounts of tritium could be found in almost all materials, thus pointing to the need for an 

acceptance limit. Incoming shipments that could result in excessive tritium levels at RFP 

continued to be monitored for verification. 

ORAUT coordinated a request for information from RFP related to communication with Pantex 

regarding the implementation of control limits for shipments. RFP responded that no 

information was available (August 8, 2013 email from Rod Hoffman). Since the time limit for 

retention of those records has expired, RFP believes that the documents may have been 

destroyed per the document retention/destruction schedule. 

Additional Comment Response: Dr. Ziemer Question

Comment: Regarding the question of why the co-worker model came up with 0 dose when there 

was dose associated with the 1974 incident, was the bioassay samples from the 1974 incident 

included in the post-1973 RFP tritium co-worker model presented in the RFP tritium white 

paper?

Response: The co-worker model was based on the analysis of the NOCTS claimant data. The 

assessed dose from the co-worker was less than 1 mrem per year, which, in terms of dose 

assignments for an individual DR under the EEOICPA program, results in a zero dose 

assignment for the purpose of calculating POC. All the NOCTS claimant data available for 1974 

were used in the co-worker study. While not all the results from the 1974 site incident report 

were added in because details regarding the individuals were incomplete, the data/results that can 

be matched with NOCTS claimants (for two individuals) were used (data from the claimant’s 

NOCTS files). No data were added from the incident report. The results matched with NOCTS 

claimants included those for one individual identified as having the largest intake from the 

incident. It is noteworthy that the largest dose from the 1974 incident was only 0.15 mrem, so 

inclusion of all of the results still wouldn’t yield a dose greater than 1 mrem. 

Additional Comment Response: SC&A Review of Tritium White Paper

Comment: SC&A reviewed the NIOSH tritium white paper and provided comments and 

feedback on the tritium dose reconstruction method presented for the 1973 period at RFP in their 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 39 of 45

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

paper titled, SC&A Review of Part II, Rocky Flats Tritium Dose Assignment for 1973, 

Attachment A.

Response: The primary NIOSH response to the SC&A review is that the SC&A analysis uses a 

draft model that is clearly identified as not for use at this time, which is acknowledged in the 

SC&A response. The Rule governing this program explicitly requires the use of currently 

approved ICRP models for the purpose of assessments and the use of such unapproved models is 

outside of the scope of the NIOSH methodology. As such, NIOSH has not performed a detailed 

analysis of the model as it relates to EEOICPA dose reconstruction or the results provided by 

SC&A in their assessment. The general observation is that it should have very little impact on 

situations outside of RFP because it only affects cases where urine samples are collected more 

than 100 days after intake, which should be a rare occurrence for tritium. It is noted that the 

SC&A paper matched the NIOSH white paper values when the bioassay was collected 50 or 60 

days after the assumed intake. If the model is approved and issued by the ICRP, it will be 

reviewed for incorporation into the EEOICPA dose reconstruction program.

One of the focuses in the SC&A assessment of the NIOSH tritium white paper was the analysis 

of Case A (from the RFP evaluation of the five highest exposed individuals from the 1973 

tritium release incident). It appears that the SC&A assessment results are approximately the 

same as the results presented in the NIOSH white paper for Case A when the same intake 

assumptions are used. The similar results occur when assessing the exposures based on the ‘best 

fit’ of the data in the model – the best fit scenario is not disputed by SC&A; rather, the SC&A 

assessment offers other possible exposure situations that were not considered plausible based on 

NIOSH’s review. The earlier intake date assumed by SC&A had been ruled out in the NIOSH 

analysis because Case A worked with Cases D and P in April and they did not exhibit similar 

excretion levels, and Case A’s elimination pattern exhibited a less-than-10-day half time, which 

is indicative of a relatively recent intake. In its review, the SC&A assessment concurs with the 

NIOSH assessment of Case D. However, as it relates to Case A, SC&A does not address that 

workers A and D (and P) worked together in April 1973 on the same project. When considered, 

there is no support for the use of the SC&A assumptions for Case A that results in the 

significantly higher dose totals. Further explained, the likelihood of one individual receiving an 

intake of 92 mCi when co-located workers received no intake, is not plausible. NIOSH 

concludes that the nature of the exposure scenario does not support large differences in personnel 

exposure; rather, it supports the use of the NIOSH best-fit analysis.

The other details discussed by SC&A regarding the use of un-distilled versus distilled samples 

support the basis that the NIOSH assessment presents a claimant-favorable approach for tritium 

dose reconstruction in the SEC period. In addition to the above thoughts regarding the 

assessment of the tritium exposures for 1973, it is important to remember that the entire period 

being assessed for tritium falls in the currently recommended SEC period (through 1983). 

Therefore, NIOSH feels that the assessments for 1973, as well as the pre- and post-1973 periods, 

represent NIOSH’s best and final approaches for reconstructing tritium at RFP within the 

associated time-periods.
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 40 of 45

This is a working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Additional Comment Response: SC&A Review of Tritium White Paper, Revision 1

Comment: SC&A reviewed the NIOSH tritium White Paper and provided comments and 

feedback on the tritium dose reconstruction methods presented for RFP in their paper titled, 

SC&A Response to NIOSH White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant 

Tritium Issues, dated May 30, 2014.

Response: The question of the representativeness of a 1974 container release incident, for which 

dose values are being back-extrapolated for all tritium releases from containers before the 1973 

event, was addressed in Revision 2 of the NIOSH white paper. The method used by NIOSH to 

assign pre-1973 doses was to assume that an event similar to that in August 1974 occurred every 

day pre-1973 and resulted in an effective dose commitment of 37.5 mrem/year to all workers. 

This value was derived based on the results of bioassay samples collected from workers 

immediately following the August 30, 1974, release of 1.5 Ci of tritium while opening a shipping 

container. Specifically, following this incident, the highest concentration of tritium in urine was 

found to be 36,320 pCi/L, which is associated with a dose commitment of 0.15 mrem. Assuming 

such an event occurs every day, and assuming that all workers worked 250 days per year, the 

annual dose for all workers from chronic exposures pre-1973 is assumed to be 37.5 mrem. The 

ABRWH had an extended discussion of the issues associated with pre-1973 exposures to tritium. 

After considerable discussion, it was agreed that this issue should be closed. This decision was 

acceptable to the Work Group as a bounding approach for reconstructing pre-1973 chronic 

tritium exposures to all workers.

Applicable post-1973 exposures and dose reconstruction issues were also addressed in in 

Revision 2 of the NIOSH white paper and/or addressed in discussions between NIOSH and the 

ABRWH. The revision addressed the numbers, locations, and representativeness of the tritium 

bubblers results. These data help to provide further information on the concentration of tritium 

in air at locations where workers might be present and are consistent with the assumption that the 

annual exposures to workers were less than 1 mrem/yr.

Issues regarding the dose reconstruction approach for worker exposure to the 1973 tritium 

release were addressed in Revision 2 of the NIOSH white paper. To address SC&A’s concerns 

regarding the dose reconstruction implications of delayed (beyond 100 days) urinalyses for 

tritium and its application to the five workers selected, NIOSH provided a written description of 

its proposed DR approach and implementation for the 1973 release. However, issues regarding 

the model used in the approach remained.

Additional Comment Response: SC&A Review of Tritium White Paper, Revision 2

Comment: SC&A reviewed Revision 2 the NIOSH tritium white paper and a remaining issue 

associated with the dose reconstruction method presented for the 1973 period at RFP was 

discussed and a resolution was proposed.
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

Page 41 of 45

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Response: Issues regarding the dose reconstruction approach for worker exposure to the 1973 

tritium release have been further addressed in Revision 3 of the NIOSH white paper. After 

considering RFP ABRWH Working Group discussions regarding the 1973 tritium model, 

NIOSH decided to adopt the use of Revision 3, incorporating the use of the tritium model 

proposed by SC&A, which is described in Review of the ICRP Tritium and C-14 Internal 

Dosimetry Models and Their Implementation in the GENMOD-PC Code, by R. B. Richardson 

and D. W. Dunford, for the assessment of 1973 RFP tritium dose 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Appendix 3: Workplace Air Tritium Monitoring at 

Rocky Flats, 1977-1981

Purpose

NIOSH requested in May 2015 that ORAUT evaluate evidence of a robust workplacemonitoring program in order to comprehensively close out the issue of RFP tritium exposure 

after 1973. This appendix establishes the locations and frequencies of workplace-monitoring at 

the Rocky Flats Plant between 1977 and 1981. The existence of a robust workplace-monitoring 

program at RFP would support the validity of bounding occupational exposures to tritium during 

and after 1973 using the analysis and co-worker model that ORAUT performed, as discussed in 

Appendix 1, Part II of this tritium follow-up paper. 

Method

NIOSH has been unable to capture digitized records describing workplace-tritium-monitoring 

programs prior to the end of plutonium processing operations2

2 Plutonium-processing operations ceased subsequent to the FBI raid in 1989 (SRDB 8016, PDF p. 12).

(with which tritium releases and 

contamination incidents are closely linked). However, the SRDB contains three handwritten logs 

of analytical results for tritium collected by bubblers used for both environmental and workplace 

air sampling (SRDB 111095; 111157; 111189). One of these logs (SRDB 111095), spanning the 

period 4/1/1977 to 12/23/1981, was evaluated by noting the locations and results for bubbler 

samples of workplace air analyzed3

3 Samples were typically analyzed within a week of collection, except over holidays.

 during the first seven-day period of each year’s records 

beginning in April 1977 and the last seven-day period of December 1981. Any location logged 

to indicate that sampling was taken from an effluent system, such as a plenum or exhaust duct, 

was excluded. Other sampling sites not otherwise clearly marked were excluded when 

documentation was found indicating that they sampled an effluent system (e.g., SRDB 24164, 

PDF p. 19) or a glovebox environment (SRDB 122692, PDF p. 9). Locations marked as a Room 

or as a support column coordinate within a room were assumed to be workplace air-sampling 

locations. 

Results

Review of the selected log (SRDB 111095) identified 107 log entries for tritium bubbler-sample 

results that are not associated with glovebox environments or effluents. The PDF page number, 

sampling location, date of analysis, and analytical result for each of these entries, grouped by 

 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

location, is provided in an Excel spreadsheet (SRDB 144998). Results range4

4 Values of zero do not appear in the record until after the first week of 1981; entries less than or equal to a value no 

greater than 170 pCi/m3 (presumably the detection limit) are used instead of zero prior to this time.

from 0 pCi/m3 to a 

high of 7,920 pCi/m3. The high value was associated with the Disassembly Area (SRDB 24164, 

PDF p. 10) at Glovebox 452 (SRDB 118366, PDF pp. 2, 5). The average value is 152.5 pCi/m3

if ‘less than’ values are treated as zero.

There are 17 separate locations in the 107 entries where bubbler results for tritium were logged. 

An occurrence matrix showing the bubbler monitoring locations and the number of analyses 

reported for each of the periods for which results were noted is shown in Table A3-1 below. 

Table A3-1: Occurrence Matrix for Bubbler Tritium Air Samples, April 1977 – December 1981

Bldg. 

Number

Sample 

Location

Apr. 1977 

Number of 

Analyses*

Jan. 1978 

Number of 

Analyses*

Jan. 1979 

Number of 

Analyses*

Jan. 1980 

Number of 

Analyses*

Jan.1981 

Number of 

Analyses*

Dec. 1981 

Number of 

Analyses*

374 First Floor No sample 

reported

No sample 

reported 2 No sample reported

No sample 

reported

No sample 

reported

559 102 No sample 

reported

No sample 

reported 1 No sample reported

No sample 

reported

No sample 

reported

771 181 No sample 

reported 1 1 No sample reported

No sample 

reported

No sample 

reported

771 305 No sample 

reported 1 No sample reported

No sample 

reported

No sample 

reported

No sample 

reported

771 Rm 146 No sample 

reported 1 1 No sample reported

No sample 

reported 5 

771 Rm 149 No sample 

reported

No sample 

reported

No sample 

reported

No sample 

reported

No sample 

reported 4 

771 Rm 174 No sample 

reported 

No sample 

reported 1 No sample reported

No sample 

reported 4 

774 220 No sample 

reported 1 No sample reported

No sample 

reported

No sample 

reported

No sample 

reported

777 430, G-18 No sample 

reported

No sample 

reported

No sample 

reported

No sample 

reported 5 4 

777 430, K-15 No sample 

reported

No sample 

reported

No sample 

reported 1 No sample reported

No sample 

reported

777 Rm 452, 

Downdraft 4 3 2 2 4 4 

777 Rm 452, 

Col J-23 4 3 3 3 4 4 

777 Rm 465 No sample 

reported

No sample 

reported

No sample 

reported

No sample 

reported

No sample 

reported 4 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Bldg. 

Number

Sample 

Location

Apr. 1977 

Number of 

Analyses*

Jan. 1978 

Number of 

Analyses*

Jan. 1979 

Number of 

Analyses*

Jan. 1980 

Number of 

Analyses*

Jan.1981 

Number of 

Analyses*

Dec. 1981 

Number of 

Analyses*

779A Rm 154 No sample 

reported 4 2 4 7 2 

881 225 No sample 

reported

No sample 

reported

No sample 

reported

No sample 

reported

No sample 

reported 1 

881 283 No sample 

reported 2 No sample reported 1 3 No sample reported

881 Rm 15 No sample 

reported

No sample 

reported

No sample 

reported

No sample 

reported

No sample 

reported 2 

*These are the numbers of work-area bubbler samples analyzed during the first seven days of records for 1977-

1981, and for the last seven days of records for 1981.

Monitoring frequencies were consistent in three of these locations during the five-year period:

1. Building 777, Room 452 (Special Assembly) Downdraft, the location of tritium released 

from a contaminated shipping container on 8/30/1974 (SRDB 8790) 

2. Building 777, Room 452, Col J-23 

3. Building 779A, Room 154, the Hydriding Laboratory (SRDB 118367, PDF p. 3) and location 

of glovebox #1363, where elevated tritium levels were seen just prior to Dec 5, 1977 (SRDB 

110903, PDF p. 2) 

The above areas were known to have elevated potential for tritium release into the workplace 

because of the prior incidents. Samples were normally retrieved from these locations three times 

weekly (Monday, Wednesday, and Friday). This sampling frequency was specified on log sheets 

prior to January 1978 (SRDB 111095, PDF p. 22) and in later radiological operating instructions 

(SRDB 24307, PDF p. 3). The same (Monday, Wednesday, and Friday) frequency was applied 

wherever glovebox environment and effluent monitoring for tritium was performed. 

Inspection of Table A3-1 above shows that areas where tritium release to the workplace was 

known to have happened in the past were monitored frequently and consistently in the five-year 

period from 1977-1981, and that other areas were monitored occasionally. Tritium limits were 

established after the 1973 release for workplace surface smears (0.005 μCi/100 cm2), effluent air 

(2 μCi/m3

), and room air (0.05 μCi/m3) (SRDB 4632, PDF p. 165). 

A brief review of two similar documents of handwritten tritium monitoring results for the years 

1974-1982 and 1974-1975, respectively, indicated similar monitoring frequencies and locations 

as those discussed here during years not included in this analysis (SRDB 111157; 111189). 
White Paper: Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 3)

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ABRWH (or their technical support and review contractors) positions, unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Summary and Conclusions

Workplace air monitoring for tritium using bubblers was performed frequently and consistently 

at the Rocky Flats Plant after 1973 in areas known to have a significant potential for personnel 

exposure. Other areas were also monitored, but less frequently, perhaps on the basis of 

production activity with a potential for tritium release. Analytical results indicate a detection 

limit almost three orders of magnitude below the 0.05 μCi/m3 limit for tritium in workplace air 

established by RFP management. The largest result noted for this analysis was 7,920 pCi/m3, 

which is 16% of the limit.

Rocky Flats continued to monitor workplace tritium well beyond the release incident in 1973 

with results indicating that tritium levels were normally quite low. NIOSH concludes that the 

use of a co-worker model for estimating and bounding tritium doses during normal operations at 

Rocky Flats is, therefore, appropriate.